Washington — Thousands more mid-level enlisted soldiers are leaving the Army than in each of the past two years, forcing the service to increase its use of pay-to-stay programs and find other ways to keep GIs in the fold.

Four years into the fight in Iraq, the Army continues to be successful in retaining enough soldiers overall – "a miracle" to some observers, because the war has lasted so long. But that success masks a growing problem within the ranks: Fewer mid-grade sergeants are opting to stay in the Army as many face yet another deployment to Iraq – and, more important, Army officials say, less time at home.

While a reenlistment shortfall in any Army group is cause for concern, many consider the declining rate among mid-grade sergeants to be a sign of potential bigger reenlistment problems for the Army down the line. In addition, the fact that more mid-level soldiers are leaving could have a long-term impact on the Army's ability to grow future leaders.

The Army has seen the reenlistment rate of mid-grade enlisted soldiers drop 12 percentage points, from 96 percent during the first quarter of 2005 to a low of 84 percent for the first quarter of 2007, according to Pentagon data. As of March, the Army is as much as 10 percentage points behind where it was in retaining mid-grade soldiers at that time in 2005 and 2006. (The overall retention goal for mid-grade soldiers in fiscal year 2006 was about 25,000.)

Although Army officials say they will make their overall retention goals by the end of the fiscal year – in September – the decline means this will be the hardest year so far when it comes to keeping soldiers in uniform since the war in Iraq began.

How bad the problem is depends on whom you ask. To some, the trend is further proof that the war in Iraq has broken the back of the Army. Others believe it remains only an ominous warning light on the Army's collective dashboard but does not mean there is a crisis.

Either way, if mid-grade soldiers do not "re-up" in enough numbers, the Army will have a problem that will only worsen if not corrected soon.

"I am not alarmed to the point that we are breaking the Army, but [the numbers] are creeping up," says Army Gen. David McKiernan, who commands Army forces in Europe. "We can't lose the leadership of the US Army, or we will be broken." [Editor's note:The original version misstated General McKiernan's rank.]

Uniformed and civilian officials, both in and outside the Pentagon, have also expressed worry about the commissioned officer corps. The "loss rate" among lieutenants and captains has climbed since the war began, from 6 percent in 2003 to 8 percent in 2006.

Army officials have expanded incentive programs to keep soldiers in, raising the ceilings on reenlistment bonuses for soldiers in specific jobs from $15,000 to $20,000. It's also paying as much as $150,000 to retain soldiers in special-forces jobs.

In addition, the service has created an extra bonus of $7,500 for those who reenlist during fiscal year 2007. Many of these bonuses are tax-free if the reenlistment occurs in a war zone.

A recent Associated Press review of bonus programs shows that the Army and Marine Corps will spend more than $1 billion on reenlistment bonuses during fiscal 2007, up from $174 million in 2003.

The service has also tried to reassign soldiers who have deployed multiple times to nondeploying jobs within the Army, says Army Sgt. Maj. Scott Kuhar, a senior Army career counselor in the Pentagon.

All this raises both short- and long-term concerns about the health of the Army, says Larry Korb, a senior fellow at the Center for American Progress, a liberal think tank in Washington.

"The Army has got a tough job," says Mr. Korb, a personnel chief at the Pentagon in the 1980s. "They didn't start this war and they probably didn't want to have it, but now they have to deal with the consequences of it."

Korb worries that various pay-to-stay programs that the Army is employing may have a long-term effect by retaining soldiers who might otherwise have gotten out. "You want the people who love the Army and want to stay in," he says. While the money keeps them in for now, Korb adds, they won't stay when the reenlistment cash disappears.

Army officials counter that the average bonus paid to reenlist a soldier – about $11,000 – is not enough to fundamentally change the nature of the Army's soldier population and is only helping get the service through this rough period.

Others are not sounding the alarm, at least not yet. One who does not see a crisis is Bernard Rostker, who left as head of the Pentagon's personnel department in 2000. "There is going to be burnout, and this war is burnout No. 1," says Mr. Rostker, a senior fellow at the RAND Corp. "The miracle is that the force is still with us, not that we're down from 96 to 84 percent. To me, that's a good news story."

Army officials have found one interesting trend among soldiers who've been polled informally on what is driving them away: While many joined the service to go to combat in a war zone, it's the lack of time at home, or "dwell time," that hurts, Sergeant Major Kuhar says.

Under a new policy, units will not deploy with less than 12 months of time at home. But the larger goal is to give them two years between deployments – a goal the military won't reach anytime soon.

"The No. 1 thing was dwell time," Kuhar says. "It came back loud and clear to us that they just want more time with their families or with their friends before they deploy."